1. Field of the Invention
The present invention relates to a method for fabricating a LiFePO4 cathode electroactive material for a lithium secondary battery by recycling, and a LiFePO4 cathode electroactive material for a lithium secondary battery, a LiFePO4 cathode, and a lithium secondary battery fabricated thereby.
2. Discussion of Related Art
A lithium ion secondary battery having improved characteristics of high capacity, high power, and long life, is widely used for small electronic products such as electronic equipment, portable computers, and cell phones. In particular, as the issues of green growth and new renewable energy receive attention, the demand for lithium ion secondary batteries is expected to rapidly increase with commercialization of electric vehicles.
Various kinds of materials for cathode active materials for a lithium ion secondary battery have been developed. Recently, as well as conventional materials such as LiCoO2 and ternary system active material (LiCo1/3Ni1/3Mn1/3O2), LiFePO4 which is an olivine-based material, is spotlighted as a cathode active material for a high-capacity lithium ion secondary battery for an electric vehicle.
In particular, since LiFePO4 is cheaper than other cathode active materials, it is expected that a high-capacity lithium ion secondary battery using LiFePO4 as a cathode active material will be commercialized soon.
Although the lithium ion battery market and industry are expected to be rapidly developed, lithium (Li) metal and related compounds which are indispensable for a cathode active material, do not exist as natural resources in this country (Korea), and are thus imported from foreign countries. Therefore, it is necessary for a country lacking natural resources to collect and recycle cathode scraps generated during a fabricating process of a lithium ion secondary battery or active materials of wasted lithium ion secondary batteries.
According to a conventional method for extracting or collecting various metals such as lithium or compounds from a cathode of a wasted lithium ion secondary battery, the cathode separated from the battery is dissolved with hydrochloric acid (HCl), sulfuric acid (H2SO4), or nitric acid (HNO3), and then is neutralized with alkali in order to precipitate and collect metals such as cobalt and nickel by using hydroxide. Or, by using a solvent extraction technique, metals such as cobalt, manganese, and nickel are separated from the cathode-dissolved solution.
As described above, cobalt and nickel are main targets of collection, and lithium, which is cheaper than cobalt or nickel, is not an object of great attention. However, lithium resources are limited, and it is highly possible to use phosphate-based LiFePO4 not containing cobalt or nickel as a cathode active material for a high-capacity lithium ion secondary battery for an electric vehicle. Therefore, collection or recycling of lithium or related compounds is expected to become a more important issue.